The present invention relates to an apparatus and a method for joining bumps formed at electrodes of an electronic component to electrode portions on a circuit board, and a semiconductor component-manufacturing apparatus provided with the bump-joining apparatus.
In one way for electrically connecting and fixing electronic components onto a circuit board, there is carried out a method whereby bumps formed at electrodes of an electronic component are joined to electrode portions on a circuit board. For instance, a semiconductor component-manufacturing apparatus 1 shown in FIG. 11 is used to execute the bump-joining method, which roughly comprises a component feed apparatus 2, a bonding stage 3, a component reversal apparatus 4, a bump-joining apparatus 5 and a circuit board transfer apparatus 6.
The component feed apparatus 2 feeds semiconductor chips as an example of the electronic components, and the circuit board transfer apparatus 6 carries circuit boards in to and out from the semiconductor component-manufacturing apparatus 1. The bonding stage 3, where one of the circuit boards carried in by the circuit board transfer apparatus 6 is loaded to be subjected to the joining, can be moved in a Y-direction by a Y-axis robot 7. The bonding stage 3 heats the circuit board for the joining of bumps. The component reversal apparatus 4 holding one of the semiconductor chips supplied from the component feed apparatus 2 turns the semiconductor chip upside down so that bumps formed at electrodes of the semiconductor chip face the circuit board loaded on the bonding stage 3. The bump-joining apparatus 5 includes a holding device for holding the semiconductor chip, a Z-directional driving device 51 for moving the held semiconductor chip in a thicknesswise direction of the semiconductor, and an ultrasonic vibration generation device 9 which will be detailed later. The bump-joining apparatus 5 is mounted to an X-axis robot 8 to be moved in an X-direction by the X-axis robot 8, receiving the semiconductor chip from the component reversal apparatus 4, transferring the semiconductor chip to the bonding stage 3, driving the Z-axis driving device 51 thereby pressing the received and held semiconductor chip at a predetermined position of the circuit board loaded on the bonding stage 3 to join the bumps. A positioning of the semiconductor chip to be joined onto the circuit board is carried out by the X-axis robot 8 and Y-axis robot 7.
The bump-joining apparatus 5 is provided with the ultrasonic vibration generation device 9 which vibrates the bumps in the Y- or X-direction thereby generating heat of friction between the bumps and electrode portions on the circuit board to decrease a heating temperature of the bonding stage and steady the joining of the bumps. The ultrasonic vibration generation device 9 has, as shown in FIG. 12, a plurality of layered piezoelectric elements 91 and an ultrasonic horn 92 connected to one end portion of the piezoelectric elements 91. A vibration, e.g., in the Y-direction brought about when a voltage is impressed to the piezoelectric elements 91 is amplified by the ultrasonic horn 92. A nozzle 93 for holding of the semiconductor chip is fixed at the other end portion of the ultrasonic horn 92. The vibration of the piezoelectric elements 91 brings about ultrasonic vibration to the nozzle 93, i.e., semiconductor chip held by the nozzle 93. Although the piezoelectric elements 91 vibrate in the Y-direction in FIG. 12, while the vibration is conducted to the semiconductor chip, vibrations moving in various directions also occur. Consequently the semiconductor chip is actually vibrated in various directions although primarily vibrated in the Y-direction.
The conventional semiconductor component-manufacturing apparatus 1 constituted as above joins the bumps in a manner described hereinbelow.
The circuit board carried in by the circuit board transfer apparatus 6 is loaded and heated on the bonding stage 3. In the meantime, the semiconductor chip held by the component reversal apparatus 4 from the component feed apparatus 2 is moved by the bump-joining apparatus 5 to a mount position on the bonding stage 3. Each of bumps 11 before being joined has a configuration, for example, as shown in FIG. 13. Specifically, a diameter I of each bump 11 is approximately 100 xcexcm, a height III of a base portion 11a is approximately 30-35 xcexcm and a total height II of each bump 11 is approximately 70-75 xcexcm.
Each bump 11 of the configuration is pressed to each electrode portion on the circuit board by the operation of the Z-directional driving device 51, pressed down as indicated in FIG. 14 and joined. A height IV of the bump 11 in FIG. 14 when pressed is nearly equal to the height III of the base portion 11a. 
In the conventional semiconductor component-manufacturing apparatus 1, after the bump 11 is pressed in a state of FIG. 14 (which will be denoted by a reference numeral 12 hereinafter), the ultrasonic vibration generation device 9 is operated to vibrate each bump 12 with ultrasonic waves and join the pressed bump 12 to each electrode portion of the circuit board.
According to the conventional art described above, each contact-area between each bump 12 and each electrode portion 21 of the circuit board 20 is large because each bump 12 is started to be vibrated only after each bump 11 is pressed to be formed as the bump 12 in FIG. 14. In consequence, a sufficient scrub or friction cannot be attained in some cases between the bump 12 and electrode portion 21, resulting in insufficiency of heat of friction necessary for the joining between the bump 12 and the electrode portion 21. The bump 12 and the electrode portion 21 cannot be joined perfectly, with a resultant decrease in the join strength.
The present invention is devised to eliminate the above-discussed disadvantage and has for its object to provide an apparatus and a method for perfectly joining bumps and electrode portions of a circuit board with larger joint strength than in the conventional art, and a semiconductor component-manufacturing apparatus including the bump-joining apparatus.
In accomplishing this and other objects, according to a first aspect of the present invention, there is provided a bump-joining apparatus for joining bumps formed at an electronic component to electrode portions on a circuit board, which comprises:
a vibration generation device for generating relative vibrations between the bumps and the electrode portions, with the bumps facing the electrode portions;
a pressing device for moving the electronic component and the circuit board relative to each other in a direction to bring the bumps and the electrode portions close to each other, and pressing the bumps of the electronic component and the electrode portions to each other, so as to compress the bumps; and
a control unit for controlling the pressing device to execute a pressing action control to change a contact-area of each of the bumps to each of the electrode portions through the compressing from an initial contact area corresponding to each of the bumps to a join-completed-contact area corresponding to each of the bumps at the completion of the joining which exceeds the initial contact area, and for controlling the vibration generation device to execute a vibration control to generate constant vibration from a time when the contact-area reaches the initial contact area to a time when the contact-area reaches the join-completed-contact area.
According to a second aspect of the present invention, there is provided a bump-joining method for joining bumps formed at an electronic component to electrode portions on a circuit board, which comprises:
with the bumps facing the electrode portions, performing a pressing operation to press the bumps and the electrode portions relatively so as to compress the bumps so that contact-areas between the bumps and the electrode portions change from initial contact areas to join-completed-contact areas at completion of the joining, with the join-completed-contact areas exceeding the initial contact areas; and
generating a constant (i.e. substantially unchanging, invariable, or uniform) vibration relatively between the bumps and the electrode portions continuously (i.e., uninterrupted) from a time when the contact-area reaches the initial contact area to a time when the contact-area reaches the join-completed-contact area, to thereby join the bumps to the electrode portions.
A semiconductor component-manufacturing apparatus according to a third aspect of the present invention features the above bump-joining apparatus of the first aspect.
According to a fourth aspect of the present invention, there is provided a bump-joining apparatus for joining bumps formed at an electronic component to electrode portions on a circuit board, which comprises:
a vibration generation device for generating relative vibration between the bumps and the electrode portions, with the bumps facing the electrode portions;
a pressing device for moving the electronic component and the circuit board relative to each other in a direction to bring the bumps and the electrode portions close to each other, and pressing the bumps of the electronic component and the electrode portions to each other, so as to compress the bumps; and
a control unit for controlling the vibration generation device and the pressing device to generate vibration before the bumps come in touch with the electrode portions until a contact-area of each of the bumps to each of the electrode portions reaches a join-completed-contact area at completion of the joining.
According to a fifth aspect of the present invention, there is provided a bump-joining method for joining bumps formed at an electronic component to electrode portions on a circuit board, which comprises:
with the bumps and electrode portions facing each other, performing a pressing operation to press the bumps and the electrode portions to each other relatively so as to compress the bumps so that contact-areas of the bumps to the electrode portions change to join-completed-contact areas at completion of the joining, wherein the join-completed contact areas exceed initial contact areas;
generating initial relative vibration between the bumps and the electrode portions, without causing misregistration of the bumps and the electrode portions, before the bumps come in contact with the electrode portions and until the contact-areas reach the initial contact areas; and
generating constant (i.e., substantially unchanging, invariable or uniform) relative vibration, exceeding the initial vibration, between the bumps and the electrode portions continuously (i.e., uninterrupted) from a time when the contact-areas reach the initial contact-areas to a time when the contact-areas reach the join-completed contact areas, so as to join the bumps to the electrode portions.
In the bump-joining apparatus according to the first aspect of the present invention and the bump-joining method according to the second aspect of the present invention, the vibration generation device, the pressing device and the control unit are provided, and the electrode portions and the bumps are vibrated relatively from a time when each of the bumps obtains the initial contact area subsequent to the pressing to a time when the initial contact area changes to the join-completed-contact area. In comparison with the conventional art wherein the vibration is applied only after the join-completed-contact area is attained, the vibration in these aspects of the present invention effectively works to generate the heat of friction from the time when each contact-area between the bumps and the electrode portions is small. So, each of the bumps is joined at an increased contact-area to each of the electrode portions. The bumps and the electrode portions are perfectly joined throughout changing of the contact-area of each of the bumps to each of the electrode portions when the contact-area becomes the join-completed-contact area. Thus larger joint strength is achieved relative the conventional art.
The semiconductor component-manufacturing apparatus according to the third aspect of the present invention comprises the bump-joining apparatus and the bump-joining method according to the first and second aspects of the present invention, whereby the electronic component and the circuit board of a produced semiconductor component are joined with larger strength than in the conventional art.
According to the bump-joining apparatus of the fourth aspect of the present invention, the bumps and the electrode portions are vibrated relatively before coming in contact with each other. Even when the bumps are nonuniform in height, the bumps can be surely joined to the electrode portions from the time when the bumps and the electrode portions come in contact with each other. Moreover, a time required for setting to achieve the initial contact area can be saved and consequently the Tact time is shortened.
In the bump-joining method according to the fifth aspect of the present invention, the vibration relatively applied to the bumps and the electrode portions is adapted to change in two levels, with the same effect as achieved by the bump-joining apparatus of the fourth aspect. The initial vibration is smaller than the vibration in the period from the initial contact area to the join-completed-contact area, thus decreasing the possibility that the holding of the electronic component is lost before the bumps and electrode portions are brought in contact with each other.